Hammer drill



July 3, 1928. 1,675,326

F. H. BLANDING HAMMER DRILL Filed Nov. 9, 1923 e L I Q N w I a:

m .N m N w I g a INVENTOR. F0/QR5JT/7. BLA/VO/NG.

4 ATTORNEY.

Patented July 3, 1928.

[UNITED STATES i 1 1,675,326 PATENT OFFICE.

ronnnsr H. BLANDING, or DETROIT, MICHIGAN, AssIGnoR To onrcaeo.PNEUMATIC.

moon COMPANY, on NEW YORK, n. Y.; A CORPORATION on NEW JERSEY.

HAMMER DRILL.

Application filed November 9, 1923. Serial No. 673,665.

This invention relates to drills of the impact type and 1n particular tomechanism for rotating the drill steel. More specifically it concernsimprovements in rifle bar rotation mechanism.

'" expense of making repairs.

vide ample bearing and engaging surfaces in the rotation mechanismthereby to provent rapid wear, and to improve the structure and theassembly of such mechanism and the parts associated therewith in orderto reduce to a minimum the time, labor and With theseand other objectsin, View, the invention will now be disclosed in detail, reference beinghad to the accompanying drawings wherein is shown one embodiment of theinvention.

In the drawings: 1 i

Fig. 1 is a longitudinal sectional view;

Fig. 2 is a transverse sectional View on an enlarged scale takensubstantially on the 22 of Fig. 1;

Fig. 3 is a view in elevation of the parts comprising the rotationmechanism in disassembled relation. 7

The embodiment of the invention chosen for the purpose of illustrationis a rock drill having a casing or cylinder 4 within which a hammerpiston 5 reciprocates by fluid pressure admitted through an intake 6(Fig. 2) and controlled by a suitable valve (not shown) mounted in anextension 7 of the casing to impart blows to and effect rotation of aworking tool 8 supported in the front head 9 of the casing. The rotativeimpulse imparted to the piston 5 by the rotation mechanism, presently tobe described, is transmitted to the tool in the usual manner as by ribs10 on the forwardend of the piston cooperating with grooves in a sleeve11 which forms part of or cooperates with the working tool chuck.

The piston 5 has rigidly but removably secured thereto in any suitablemanner a rifle bar 12. In the form shown, the end of the rifle bar isthreaded into a shallow recess 13 in the rear end of the piston. Theribs of the rifle bar cooperate with the grooves in an elongate riflenut 14 rotatively mounted in an axial extension of the piston chamberformed by the cylinder ring 15 and back head 16 of the casing. As shown,the 1t has differential bearings 17 and 18 journalled respectively inthe ring 15 and back head 16, the ring thus. serving as an aligningmember for the nut. Upon the portion 19 of the nut- 14 intermediatethese bearings a pawl carrier 20 in .the form of a' ring having pawls 21is securely butremovably fastened as by a threaded connection. Thepawlcarrier 20 fits in a counter bore 22 in the back head 16, the pawls 21coacting with a ratchet ring 23 removably secured in the counter bore,the method of attachment illustrated being by threaded connection. Thefront head 9 and back head 16 are clamped to the casing 4 in the usualmanner as by through bolts 24' (Fig. 2). If a hollow drill steel is tobe used, the piston and rifle bar may be provided with the usual axialbore 25 for receiving the water tube 26, the rear end of which issecured and packed against leakage in a socket 27 therefor in theextreme rear of the back head 16.

When the drill is in operation, the rifle bar 12 reciprocates in theextension of the piston chamber in an obvious manner, the rifle nutbeingheld against rotation by its pawls 21 on one stroke of the piston,preferably the rearward stroke, so that the assembled piston and riflebar is forced to rotate, as the rifle bar is forced through the nutunder fluid pressure. On the reverse or forward stroke, the pawls 21release the nut which then rotates with the bar and piston, permittingthe piston to strike a free and forceful blow on the working tool.

From the above it will be apparent that the attachment of the rifle barto the piston without requiring a deep bore therein as is customary indevices of this kind avoids the .weakness in this member heretoforeexperienced which frequently resulted in breakage due to the strains andshocks to which this member is subjected. By the use of a rifle nut ofsubstantial length, provision is made for ample bearing surface for thesame in the extension of the piston chamber, as well as an increasedarea of contact between the ribs of the bar and nut respectively,thereby decreasing the wear and prolonging the life of these parts. Bymaking the rotation mechanism in comparatively small, separable unitsreadily assembled and removed in case of breakage, the time lostand ex:pense involved in repairs is reduced to a minimum. In addition thisconstruction p rm ts economies in production.

ieounterbore in the outer end of said cavity (for cooperation with saidbar, an intermediatealigning member between said back head \Vhile whatis now considered to be the preferred form of the invention has beenherein illustrated and described, it is to be understood that theinvention is not limited to the specific form and arrangement of partsshown but is capable of all changes and modifications coming within thescope of the appended claims.

Having now described my invention,-what I claim and desire to secure byLetters Patent is:

1. In a percussive drill, a cylinder forming apiston chamber, asubstantially solid piston reciprocable therein "for striking upon andfor transmitting rotation to a Working tool, a rifle'bar rigidlybutdetachably secured to said piston, a back head secured to said cylinderandhaving an axial cavity into which said rifle bar extends,a rifle nutreceived and rotatably supported in a and. cylinder forming abea-ringfor said nut, a pawlrcarrier detachably secured to said nut, and aiatchet ring on said back head engaged bythe pawls of said carrierwhereby said nut is'held against. rotation in one directionto force thecombined piston and rifle bar to rotate during movement of the latter inone direction.

2 In apercussive drill, a cylinder forming a piston chamber, asubstantially solid .piston reciprocable therein for striking upon andtransmitting rotation to a Working tool, said-pistonhaving a recess inits rearward end, a rifle bar having screw threaded engage'ment in saidrecess, a back headzin engagement with said cylinder and having an axialcavity into which said riflelzbar extends, an elongate riflenutzrotatably supported in a counterbore in the outer end of said cavity

